In vivo antileishmanial activity and chemical profile of polar extract from Selaginella sellowii

The polar hydroethanolic extract from Selaginella sellowii(SSPHE) has been previously proven active on intracellular amastigotes (in vitro test) and now was tested on hamsters infected with Leishmania (Leishmania) amazonensis (in vivo test). SSPHE suppressed a 100% of the parasite load in the infection site and draining lymph nodes at an intralesional dose of 50 mg/kg/day × 5, which was similar to the results observed in hamsters treated with N-methylglucamine antimonate (Sb) (28 mg/Kg/day × 5). When orally administered, SSPHE (50 mg/kg/day × 20) suppressed 99.2% of the parasite load in infected footpads, while Sb suppressed 98.5%. SSPHE also enhanced the release of nitric oxide through the intralesional route in comparison to Sb. The chemical fingerprint of SSPHE by high-performance liquid chromatography with diode-array detection and tandem mass spectrometry showed the presence of biflavonoids and high molecular weight phenylpropanoid glycosides. These compounds may have a synergistic action in vivo. Histopathological study revealed that the intralesional treatment with SSPHE induced an intense inflammatory infiltrate, composed mainly of mononuclear cells. The present findings reinforce the potential of this natural product as a source of future drug candidates for American cutaneous leishmaniasis.

In vitro activity of the hydroethanolic extract and biflavonoids isolated from Selaginella sellowii on Leishmania (Leishmania) amazonensis

This study is the first phytochemical investigation of Selaginella sellowii and demonstrates the antileishmanial activity of the hydroethanolic extract from this plant (SSHE), as well as of the biflavonoids amentoflavone and robustaflavone, isolated from this species. The effects of these substances were evaluated on intracellular amastigotes of Leishmania (Leishmania) amazonensis, an aetiological agent of American cutaneous leishmaniasis. SSHE was highly active against intracellular amastigotes [the half maximum inhibitory concentration (IC50) = 20.2 µg/mL]. Fractionation of the extract led to the isolation of the two bioflavonoids with the highest activity: amentoflavone, which was about 200 times more active (IC50 = 0.1 μg/mL) and less cytotoxic than SSHE (IC50 = 2.2 and 3 μg/mL, respectively on NIH/3T3 and J774.A1 cells), with a high selectivity index (SI) (22 and 30), robustaflavone, which was also active against L. amazonensis (IC50 = 2.8 µg/mL), but more cytotoxic, with IC50 = 25.5 µg/mL (SI = 9.1) on NIH/3T3 cells and IC50 = 3.1 µg/mL (SI = 1.1) on J774.A1 cells. The production of nitric oxide (NO) was lower in cells treated with amentoflavone (suggesting that NO does not contribute to the leishmanicidal mechanism in this case), while NO release was higher after treatment with robustaflavone. S. sellowii may be a potential source of biflavonoids that could provide promising compounds for the treatment of cutaneous leishmaniasis.

Pharmacodynamic and Pharmacokinetic Studies of β-Cyclodextrin:Dexamethasone Acetate Complexes in Mice

The aim of this study was to evaluate the in vivo activity of the anti-inflammatory and analgesic effects of a suspension of the complex composed of dexamethasone acetate (DMA) with β-cyclodextrin in comparison to a suspension of the pure DMA. Solid complexes prepared by different methods were evaluated in pharmacodynamics and pharmacokinetics studies. The pharmacodynamic effect was investigated although the capacity of the inhibited the inflammation. Models of abdominal constriction, carrageenan-induced paw oedema and formalin induced licking were used. The study of the pharmacodynamic comparison of free DMA and products of β-CD:DMA demonstrated no significant difference in the majority of the tests performed. Plasma concentrations of DMA and DMA:β-CD were assayed by HPLC. A significant (p > 0.05) decrease in the relative bioavailability was obtained with the suspension containing the DMA:β-CD complex as measured by DMA plasma levels. The area under the curve (AUC) of the suspension of DMA was higher than that obtained with the suspension of the complexes. The pharmacokinetic evaluation of dexamethasone carried out on mice in the present study showed that complexed DMA with β-cyclodextrin modifieds some parameters related to the phases of absorption and elimination of this drug.

Avaliação da influência de adjuvantes não-poliméricos solúveis na liberação do nimodipino a partir de formulações matriciais de liberação prolongada / Evaluation of soluble non-polymeric adjuvants in the release of nimodipino from controlled release matrices formulations

Fármacos com características lipofílicas costumam apresentar velocidade de difusão muito baixa a partir de matrizes hidrofílicas de liberação, comprometendo a obtenção de níveis plasmáticos terapeuticamente efetivos. Contudo, a liberação de fármacos lipossolúveis a partir de sistemas matriciais é influenciada pelo pH do meio, que pode facilitar a formação de cargas na molécula, melhorando sua performance. O objetivo deste trabalho foi avaliar a capacidade de adjuvantes não poliméricos em facilitar a solubilização do Nimodipino, “in vitro”, através do perfil de dissolução de cápsulas matriciais de hidroxipropilmetilcelulose (HPMC). As formulações desenvolvidas apresentaram o mecanismo de liberação do fármaco pela matriz governado pelo processo de erosão de acordo com o modelo cinético de Korsmeyer-Peppas, onde n>1. Entretanto algumas formulações apresentaram 0.5> n < 1 demonstrando ser um sistema anômalo dependente de difusão e erosão. Os perfis de dissolução nos dois meios testados mostraram-se distintos podendo observar diferenças significativas entre eles.

Drugs with slow solubility present very low diffusion from hydrophilic matrices, committing the serum levels therapeutically effectives. However, the liberation of lipophilic drugs starting from matrix systems is influenced by the pH of the medium, that it can facilitate the formation of charges in the molecule, improving your performance. The objective of this work was to evaluate the capacity of non-polymeric excipients in facilitating the solubilization of Nimodipino “in vitro”, through the capsules dissolution profiles of hydroxypropylmethylcellulose matrices. The developed formulations presented the release mechanism of drug influenced by erosion process according with the kinetic model of Korsmeyer-Peppas, where n>1. However, some formulations presented 0.5> n <1 demonstrating to be an anomalous system dependent of diffusion and erosion. The dissolution profiles in the two tested mediums showed different, allowing to observe significant differences among them.

Avaliação in vitro de medicamentos de liberação prolongada: aplicação de métodos estatísticos, modelos dependentes e independentes de análise / In vitro evaluation of controlled release drugs: application of statistic methods, dependent and independent models of analysis

O estudo teórico e tecnológico de fármacos de liberação prolongada vem se difundido, principalmente nas últimas quatro décadas, o que pode ser confirmado pelo número de trabalhos publicados desde então. Medicamentos de liberação prolongada são utilizados com o objetivo de estender o período de ação farmacológica de uma substância terapêutica e/ou para liberar o fármaco em determinada local do organismo. A liberação estendida melhora a posologia de diversos fármacos otimizando a adesão ao tratamento. No entanto, nem todos fármacos são bons candidatos a este tipo de formulação, devendo este possuir características físico-químicas adequadas. Várias alternativas para o desenvolvimento e avaliação de apresentações de liberação prolongada são disponíveis. O objetivo deste trabalho é apresentar uma revisão acerca dos métodos utilizados na avaliação do mecanismo de liberação de fármacos a partir de sistemas de liberação prolongada. Para tanto modelos de análise dependentes e independentes são apresentados, bem como modelos estatísticos